Automatic transmission fluid

ABSTRACT

Provided are compositions for use in Automatic Transmission Fluids, and more specifically to Automatic Transmission Fluids made using Gas-to-Liquids lubricant base oils, formulated with minimal to no polymeric Viscosity Index improvers. 
     The automatic transmission fluids disclosed herein contain a) a lubricant base oil having a Viscosity Index greater than a Viscosity Index Factor as calculated by the following equation: 
       Viscosity Index Factor=28×ln(Kinematic Viscosity at 100° C.)+90;         b) an automatic transmission fluid additive package; and   c) less than 1.0 wt % Viscosity Index improver. The automatic transmission fluid has a kinematic viscosity at −7° C. of less than 300 mm 2 /s, and a kinematic viscosity at 100° C. between 5.0 and 6.0 mm 2 /s.

RELATED APPLICATION

The present application claims priority to U.S. Provisional ApplicationSer. No. 60/900,093, filed Feb. 8, 2007, which is incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

The present invention relates to compositions for use in AutomaticTransmission Fluids, and more specifically to Automatic TransmissionFluids made using Gas-to-Liquids lubricant base oils, formulated withminimal to no polymeric Viscosity Index improvers.

BACKGROUND OF THE INVENTION

Automatic transmission fluids are lubricants used in motor vehicletransmissions. Different types of automatic transmission fluids are useddepending on the design and severity of application. Generally,automatic transmission fluids are designed to meet specific manufacturerrequirements.

An automatic transmission is composed of a complex variety of mechanicalparts which operate at close tolerances. The purpose of automatictransmission fluid is to lubricate these close-fitting parts to reducewear and to keep down temperature increases due to friction. To performthis function, the automatic transmission fluid must maintain itsviscosity within certain specifications. Achieving this function iscomplicated by the changing temperatures under which the transmission isoperated. It is desirable that an automatic transmission fluid performwell in all the various temperature conditions under which thetransmission will operate.

For example, in a Northern location, the automatic transmission fluidmay be below 0° C. prior to use and then heat up to over 149° C. duringuse. As automatic transmissions evolve, the maximum viscosity at lowtemperatures is reduced since too viscous an automatic transmissionfluid will not adequately flow as needed to actuate the hydraulic valvesand other hydraulic mechanisms of the automatic transmission. Automobilemanufacturers have recently changed their specifications for automatictransmission fluid to require lower maximum viscosities at lowtemperatures. The next generation automatic transmissions will requirenext generation automatic transmission fluids, especially to be surethat the automatic transmission fluid flows adequately at lowtemperatures. For example, new generation automatic transmission fluidsmust have Brookfield viscosities at −40° C. of less than 10,000 mPas,13,000 mPas, or 17,500 mPas. Current requirements for automatictransmission fluids typically only require a Brookfield viscosity at 40°C. of less than 20,000 mPas.

EP 1062305 is directed to an easily biodegradable low viscosity, lowNoack volatility lube oil material having a viscosity index in the rangeof about 110-145, >98% saturates useful as lube oil basestock, automatictransmission fluid (ATF) basestock or blending stock. The lube oilmaterial is produced by the isomerization of a wax feed having aviscosity of from 4 to 10 mm²/s at 100° C. and containing less thanabout 25% oil in wax.

EP 1366138 discloses an automatic transmission fluid having a kinematicviscosity at 100° C. of between more than 4 and 10 mm²/s, a dynamicviscosity at −40° C. of less than 10000 mPa·s comprising an additivepackage and a base oil, wherein the base oil fraction comprises at least98 wt % saturates, of which saturates fraction the content ofcyclo-paraffins is between 10 and 40 wt % and wherein the pour point ofthe base oil is less than −25° C.

EP 1632549 discloses an automatic transition fluid compositioncomprising a base oil prepared from a Fischer-Tropsch product. The baseoil may have a pour point of below −40° C. and may have a kinematicviscosity at 100° C. of between 3 and 6 mm²/s. The composition maycomprises one or more of the following performance additives being anantiwear agent, an antioxidant, an ashless dispersant, a pour pointdepressant, and antifoam agent, a friction modifier, a corrosioninhibitor and a viscosity modifier.

An Automatic Transmission Fluid (ATF) having too low a viscosity athigher operating temperatures will not provide sufficient protection totransmission components. However, an ATF having too high a viscosity atlower operating temperatures will have a negative influence on fueleconomy. In order to avoid having too low a viscosity at higheroperating temperatures and too high a viscosity at lower operatingtemperatures, an ATF needs to display a high Viscosity Index.Conventional lubricant base oils do not have sufficiently high ViscosityIndexes to meet those requirements. Therefore, when formulated as ATFs,these conventional lubricant base oils normally incorporate a polymericViscosity Index improver. However, when these ATF formulations areutilized in applications, the polymer molecules of the Viscosity Indeximprovers can be cleaved, leading to a permanent reduction in theviscosity of the fluid, which limits the applications in which the fluidcan be used.

Accordingly, it would be advantageous to identify an ATF that does notrequire Viscosity Index improver. The ATF of the present invention meetsthis need.

SUMMARY OF THE INVENTION

Provided is an automatic transmission fluid comprising: a) a lubricantbase oil having a Viscosity Index greater than a Viscosity Index Factoras calculated by the following equation:

Viscosity Index Factor=28×ln(Kinematic Viscosity at 100° C.)+90

(wherein ln refers to the natural logarithm, which is the logarithm tothe base e);

b) an automatic transmission fluid additive package; and c) less than1.0 wt % Viscosity Index improver. The automatic transmission fluid hasa kinematic viscosity at −7° C. of less than 300 mm²/s, and a kinematicviscosity at 100° C. between 5.0 and 6.0 mm²/s.

Also provided is an automatic transmission fluid comprising a lubricantbase oil, the lubricant base oil having a Viscosity Index greater than aViscosity Index Factor plus 15, wherein the Viscosity Index Factor iscalculated by the following equation:

Viscosity Index Factor=28×ln(Kinematic Viscosity at 100° C.)+90.

The automatic transmission fluid has a kinematic viscosity at −7° C. ofless than 300 mm²/s and a kinematic viscosity at 100° C. between 5.0 and7.0 mm²/s.

Additionally provided is a process for producing an automatictransmission fluid comprising: a) providing a lubricant base oil havinga Viscosity Index greater than a Viscosity Index Factor as calculated bythe following equation:

Viscosity Index Factor=28×ln(Kinematic Viscosity at 100° C.)+90;

b) blending the lubricant base oil fraction with an automatictransmission fluid additive package; and c) isolating an automatictransmission fluid comprising less than 1.0 wt % Viscosity Indeximprover. The automatic transmission fluid has a kinematic viscosity at−7° C. of less than 300 mm²/s, and a kinematic viscosity at 100° C.between 5.0 and 7.0 mm²/s.

Further provided is a process for producing an automatic transmissionfluid comprising: a) performing a Fischer-Tropsch synthesis to provide aproduct stream; b) isolating from the product stream a waxy feed; c)hydroisomerizing the waxy feed using a shape selective intermediate poresize molecular sieve comprising a noble metal hydrogenation componentunder conditions of about 316° C. to about 399° C.; d) isolating anisomerized oil; e) hydrofinishing the isomerized oil to provide aFischer-Tropsch derived lubricant base oil having a Viscosity Indexgreater than a Viscosity Index Factor as calculated by the followingequation:

Viscosity Index Factor=28×ln(Kinematic Viscosity at 100° C.)+90;

f) blending the Fischer-Tropsch derived lubricant base oil with anautomatic transmission fluid additive package; and g) isolating anautomatic transmission fluid comprising less than 1.0 wt % ViscosityIndex improver. The automatic transmission fluid has a kinematicviscosity at −7° C. of less than 300 mm²/s, and a kinematic viscosity at100° C. between 5.0 and 7.0 mm²/s.

In addition, provided is a process for producing an automatictransmission fluid comprising: a) performing a Fischer-Tropsch synthesisto provide a product stream; b) isolating from the product stream a waxyfeed; c) hydroisomerizing the waxy feed using a shape selectiveintermediate pore size molecular sieve comprising a noble metalhydrogenation component under conditions of about 316° C. to about 399°C.; d) isolating an isomerized oil; e) vacuum distilling the isomerizedoil to provide a lubricant base oil; f) hydrofinishing the lubricantbase oil to provide a Fischer-Tropsch derived lubricant base oil havinga Viscosity Index greater than a Viscosity Index Factor as calculated bythe following equation:

Viscosity Index Factor=28×ln(Kinematic Viscosity at 100° C.)+90;

g) blending the Fischer-Tropsch derived lubricant base oil with anautomatic transmission fluid additive package; and h) isolating anautomatic transmission fluid comprising less than 1.0 Wt % ViscosityIndex improver. The intermediate pore size molecular sieve selected fromthe group consisting of SAPO-11, SAPO-31, SAPO-41, SM-3, ZSM-22, ZSM-23,ZSM-35, ZSM-48, ZSM-57, SSZ-32, offretite, ferrierite, and combinationsthereof and the noble metal hydrogenation component is selected from thegroup consisting of platinum, palladium, and combinations thereof. Theautomatic transmission fluid has a kinematic viscosity at −7° C. of lessthan 300 mm²/s, and a kinematic viscosity at 100° C. between 5.0 and 7.0mm²/s.

DETAILED DESCRIPTION OF THE INVENTION

As described herein, an ATF was formulated using Gas-to-Liquids (GTL)lubricant base oils. As a result of the inherently high Viscosity Indexof the GTL lubricant base oils, the ATF could be formulated with minimalpolymeric Viscosity Index improver, for example, no polymeric ViscosityIndex improver. Typically a Viscosity Index improver modifies theviscometric characteristics of lubricants by reducing the rate ofthinning with increasing temperature and the rate of thickening with lowtemperatures. The problem of viscosity reduction in service as a resultof degradation of the Viscosity Index improver is avoided by the absenceof this additive. Moreover, the ATFs as described herein exhibitimproved fuel economy due to the high viscosity index of the lubricantbase oil used in formulating the ATFs.

Definitions and Terms

The following terms will be used throughout the specification and willhave the following meanings unless otherwise indicated.

“Fischer-Tropsch derived” means that the product, fraction, or feedoriginates from or is produced at some stage by a Fischer-Tropschprocess.

“Brookfield Viscosity”, or the low-temperature, low-shear-rate viscosityof automotive fluid lubricants at low temperatures, is measuredaccording to ASTM D2983-04a.

“Kinematic viscosity” is a measurement of the resistance to flow of afluid under gravity. Many lubricant base oils, ATFs made from them, andthe correct operation of equipment depends upon the appropriateviscosity of the fluid being used. Kinematic viscosity is determined byASTM D445-06. The results are reported in centistokes (mm²/s).

“Viscosity Index” (VI) is an empirical, unitless number indicating theeffect of temperature change on the kinematic viscosity of the oil.Liquids change viscosity with temperature, becoming less viscous whenheated; the higher the Viscosity Index of an oil, the lower its tendencyto change viscosity with temperature. High Viscosity Index lubricantsare needed wherever relatively constant viscosity is required at widelyvarying temperatures. For example, in an automobile, engine oil mustflow freely enough to permit cold starting, but must be viscous enoughafter warm-up to provide full lubrication. Viscosity index may bedetermined as described in ASTM D2270-04.

The “Viscosity Index Factor” of a lubricant base oil is an empiricalnumber derived from kinematic viscosity of the lubricant base oil. TheViscosity Index Factor of a lubricant base oil is calculated by thefollowing equation:

Viscosity Index Factor=28×ln(Kinematic Viscosity at 100° C.)+90.

The lubricant base oils used in the ATFs of the present invention have aViscosity Index greater than the Viscosity Index Factor.

Lubricant Base Oil

The lubricant base oils used in the ATFs of the present invention aremade by process comprising providing a waxy feed and thenhydroisomerizing the waxy feed as described herein. In some embodiments,the waxy feed is hydroisomerized using a shape selective intermediatepore size molecular sieve comprising a noble metal hydrogenationcomponent under conditions of about 316° C. to 399° C.

In certain embodiments, the lubricant base oil is a Gas-to-Liquids (GTL)lubricant base oil, for example, the waxy feed is Fischer-Tropschderived. The lubricant base oil is optionally made by a Fischer-Tropschsynthesis process followed by hydroisomerization of the waxy fractionsof the Fischer-Tropsch syncrude.

The lubricant base oils used in the ATFs of the present invention incertain embodiments have a Viscosity Index greater than a ViscosityIndex greater than a Viscosity Index Factor of the lubricant base oil ascalculated by the following equation:

Viscosity Index Factor=28×ln(Kinematic Viscosity at 100° C.)+90.

In certain embodiments, the lubricant base oils used in the ATFs of thepresent invention have a difference between the Viscosity Index and theViscosity Index Factor of the lubricant base oil of greater than 5, andin other embodiments, a difference between the Viscosity Index and theViscosity Index Factor of the lubricant base oil of greater than 15.

Waxy Feed

Suitable waxy feeds have high levels of n-paraffins and are low inoxygen, nitrogen, sulfur, and elements such as aluminum, cobalt,titanium, iron, molybdenum, sodium, zinc, tin, and silicon. The waxyfeeds useful in this invention have greater than 40 weight percentn-paraffins, less than 1 weight percent oxygen, less than 25 ppm totalcombined nitrogen and sulfur, and less than 25 ppm total combinedaluminum, cobalt, titanium, iron, molybdenum, sodium, zinc, tin, andsilicon. In certain embodiments, the waxy feeds have greater than 50weight percent n-paraffins, less than 0.8 weight percent oxygen, lessthan 20 ppm total combined nitrogen and sulfur, and less than 20 ppmtotal combined aluminum, cobalt, titanium, iron, molybdenum, sodium,zinc, tin, and silicon. In other embodiments, the waxy feeds havegreater than 75 weight percent n-paraffins, less than 0.8 weight percentoxygen, less than 20 ppm total combined nitrogen and sulfur, and lessthan 20 ppm total combined aluminum, cobalt, titanium, iron, molybdenum,sodium, zinc, tin, and silicon.

Waxy feeds useful in this invention are expected to be plentiful andrelatively cost competitive in the near future as large-scaleFischer-Tropsch synthesis processes come into production. TheFischer-Tropsch synthesis process provides a way to convert a variety ofhydrocarbonaceous resources into products usually provided by petroleum.In preparing hydrocarbons via the Fischer-Tropsch process, ahydrocarbonaceous resource, such as, for example, natural gas, coal,refinery fuel gas, tar sands, oil shale, municipal waste, agriculturalwaste, forestry waste, wood, shale oil, bitumen, crude oil, andfractions from crude oil, is first converted into synthesis gas which isa mixture comprising carbon monoxide and hydrogen. The synthesis gas isfurther processed into syncrude. Syncrude prepared from theFischer-Tropsch process comprises a mixture of various solid, liquid,and gaseous hydrocarbons. Those Fischer-Tropsch products which boilwithin the range of lubricating base oil contain a high proportion ofwax which makes them ideal candidates for processing into base oil.Accordingly, Fischer-Tropsch wax represents an excellent feed forpreparing high quality base oils according to the process of theinvention. Fischer-Tropsch wax is normally solid at room temperatureand, consequently, displays poor low temperature properties, such aspour point and cloud point. However, following hydroisomerization of thewax, Fischer-Tropsch derived base oils having excellent low temperatureproperties may be prepared.

Fischer-Tropsch Synthesis

The Fischer-Tropsch synthesis process provides a way to convert avariety of hydrocarbonaceous resources into products usually provided bypetroleum. In preparing hydrocarbons via the Fischer-Tropsch process, ahydrocarbonaceous resource, such as, for example, natural gas, coal,refinery fuel gas, tar sands, oil shale, municipal waste, agriculturalwaste, forestry waste, wood, shale oil, bitumen, crude oil, andfractions from crude oil, is first converted into synthesis gas which isa mixture comprising carbon monoxide and hydrogen. The feedstock for theFischer-Tropsch process may come from a wide variety ofhydrocarbonaceous resources, including biomass, natural gas, coal, shaleoil, petroleum, municipal waste, derivatives of these, and combinationsthereof.

In Fischer-Tropsch chemistry, syngas is converted to liquid hydrocarbonsby contact with a Fischer-Tropsch catalyst under reactive conditions.Typically, methane and optionally heavier hydrocarbons (ethane andheavier) can be sent through a conventional syngas generator to providesynthesis gas. Generally, synthesis gas contains hydrogen and carbonmonoxide, and may include minor amounts of carbon dioxide and/or water.The presence of sulfur, nitrogen, halogen, selenium, phosphorus andarsenic contaminants in the syngas is undesirable. For this reason anddepending on the quality of the syngas, in some embodiments sulfur andother contaminants may be removed from the feed before performing theFischer-Tropsch chemistry. Means for removing these contaminants arewell known to those of skill in the art. For example, ZnO guardbeds maybe used to remove sulfur impurities. Means for removing othercontaminants are well known to those of skill in the art. It also may bedesirable to purify the syngas prior to the Fischer-Tropsch reactor toremove carbon dioxide produced during the syngas reaction and anyadditional sulfur compounds not already removed. This can beaccomplished, for example, by contacting the syngas with a mildlyalkaline solution (e.g., aqueous potassium carbonate) in a packedcolumn.

In the Fischer-Tropsch process, contacting a synthesis gas comprising amixture of H₂ and CO with a Fischer-Tropsch catalyst under suitabletemperature and pressure reactive conditions forms liquid and gaseoushydrocarbons. The Fischer-Tropsch reaction is typically conducted attemperatures of about 149° C. to about 371° C.), optionally about 204°C. to about 288° C.); pressures of about 10-600 psia, (0.7-41 bars),optionally about 30-300 psia, (2-21 bars); and catalyst space velocitiesof about 100-10,000 cc/g/hr, optionally about 300-3,000 cc/g/hr.Examples of conditions for performing Fischer-Tropsch type reactions arewell known to those of skill in the art.

The products of the Fischer-Tropsch synthesis process may range from C₁to C₂₀₀₊ with a majority in the C₅ to C₁₀₀₊ range. The reaction can beconducted in a variety of reactor types, such as fixed bed reactorscontaining one or more catalyst beds, slurry reactors, fluidized bedreactors, or a combination of different type reactors. Such reactionprocesses and reactors are well known and documented in the literature.

The slurry Fischer-Tropsch process utilizes superior heat (and mass)transfer characteristics for the strongly exothermic synthesis reactionand is able to produce relatively high molecular weight, paraffinichydrocarbons when using a cobalt catalyst. In the slurry process, asyngas comprising a mixture of hydrogen and carbon monoxide is bubbledup as a third phase through a slurry which comprises a particulateFischer-Tropsch type hydrocarbon synthesis catalyst dispersed andsuspended in a slurry liquid comprising hydrocarbon products of thesynthesis reaction which are liquid under the reaction conditions. Themole ratio of the hydrogen to the carbon monoxide may broadly range fromabout 0.5 to about 4, but is more typically within the range of fromabout 0.7 to about 2.75 and optionally from about 0.7 to about 2.5. Anexample of a useful Fischer-Tropsch process is taught in EP 0609079,also completely incorporated herein by reference for all purposes.

In general, Fischer-Tropsch catalysts contain a Group VIII transitionmetal on a metal oxide support. The catalysts may also contain a noblemetal promoter(s) and/or crystalline molecular sieves. SuitableFischer-Tropsch catalysts comprise one or more of Fe, Ni, Co, Ru and Re.A useful Fischer-Tropsch catalyst comprises effective amounts of cobaltand one or more of Re, Ru, Pt, Fe, Ni, Th, Zr, Hf, U, Mg and La on asuitable inorganic support material, optionally one which comprises oneor more refractory metal oxides. In general, the amount of cobaltpresent in the catalyst is between about 1 and about 50 weight percentof the total catalyst composition. The catalysts can also contain basicoxide promoters such as ThO₂, La₂O₃, MgO, and TiO₂, promoters such asZrO₂, noble metals (Pt, Pd, Ru, Rh, Os, Ir), coinage metals (Cu, Ag,Au), and other transition metals such as Fe, Mn, Ni, and Re. Suitablesupport materials include alumina, silica, magnesia and titania ormixtures thereof. Some supports for cobalt containing catalysts comprisetitania. Useful catalysts and their preparation are known andillustrated in U.S. Pat. No. 4,568,663, which is intended to beillustrative but non-limiting relative to catalyst selection.

Certain catalysts are known to provide chain growth probabilities thatare relatively low to moderate, and the reaction products include arelatively high proportion of low molecular (C₂₋₈) weight olefins and arelatively low proportion of high molecular weight (C₃₀₊) waxes. Certainother catalysts are known to provide relatively high chain growthprobabilities, and the reaction products include a relatively lowproportion of low molecular (C₂₋₈) weight olefins and a relatively highproportion of high molecular weight (C₃₀₊) waxes. Such catalysts arewell known to those of skill in the art and can be readily obtainedand/or prepared.

The product from a Fischer-Tropsch process contains predominantlyparaffins. The products from Fischer-Tropsch reactions generally includea light reaction product and a waxy reaction product. The light reactionproduct (i.e., the condensate fraction) includes hydrocarbons boilingbelow about 371° C. (e.g., tail gases through middle distillate fuels),largely in the C₅-C₂₀ range, with decreasing amounts up to about C₃₀.The waxy reaction product (i.e., the wax fraction) includes hydrocarbonsboiling above about 316° C. (e.g., vacuum gas oil through heavyparaffins), largely in the C₂₀₊ range, with decreasing amounts down toC₁₀.

Both the light reaction product and the waxy product are substantiallyparaffinic. The waxy product generally comprises greater than 70 weight% normal paraffins, and often greater than 80 weight % normal paraffins.The light reaction product comprises paraffinic products with asignificant proportion of alcohols and olefins. In some cases, the lightreaction product may comprise as much as 50 weight %, and even higher,alcohols and olefins. It is the waxy reaction product (i.e., the waxfraction or waxy feed) that is used as a feedstock to a process forproviding the lubricant base oil used in the ATFs according to thepresent invention.

The lubricant base oils used in the ATFs according to the presentinvention are prepared from the waxy fractions of the Fischer-Tropschsyncrude by a process including hydroisomerization. The lubricant baseoils used in the ATFs according to the present invention may bemanufactured at a site different from the site at which the componentsof the ATFs are received and blended.

Hydroisomerization

The waxy feeds are subjected to a process comprising hydroisomerizationto provide the lubricant base oils used in the ATFs according to thepresent invention.

Hydroisomerization is intended to improve the cold flow properties ofthe lubricant base oil by the selective addition of branching into themolecular structure. Hydroisomerization ideally will achieve highconversion levels of the waxy feed to non-waxy iso-paraffins while atthe same time minimizing the conversion by cracking. In someembodiments, the conditions for hydroisomerization in the presentinvention are controlled such that the conversion of the compoundsboiling above about 371° C. in the wax feed to compounds boiling belowabout 371° C. is maintained between about 10 and 50 weight %, optionallybetween 15 and 45 weight %.

According to the present invention, hydroisomerization is conductedusing a shape selective intermediate pore size molecular sieve.Hydroisomerization catalysts useful in the present invention comprise ashape selective intermediate pore size molecular sieve and optionally acatalytically active metal hydrogenation component on a refractory oxidesupport. The phrase “intermediate pore size”, as used herein, means aneffective pore aperture in the range of from about 3.9 to about 7.1 Åwhen the porous inorganic oxide is in the calcined form. The shapeselective intermediate pore size molecular sieves used in the practiceof the present invention are generally 1-D 10-, 11- or 12-ring molecularsieves. In some embodiments of the invention, the molecular sieves areof the 1-D 10-ring variety, where 10-(or 11- or 12-) ring molecularsieves have 10 (or 11 or 12) tetrahedrally-coordinated atoms (T-atoms)joined by oxygens. In the 1-D molecular sieve, the 10-ring (or larger)pores are parallel with each other, and do not interconnect. Note,however, that 1-D 10-ring molecular sieves which meet the broaderdefinition of the intermediate pore size molecular sieve but includeintersecting pores having 8-membered rings may also be encompassedwithin the definition of the molecular sieve of the present invention.The classification of intrazeolite channels as 1-D, 2-D and 3-D is setforth by R. M. Barrer in Zeolites, Science and Technology, edited by F.R. Rodrigues, L. D. Rollman and C. Naccache, NATO ASI Series, 1984 whichclassification is incorporated in its entirety by reference (seeparticularly page 75).

Some shape selective intermediate pore size molecular sieves used forhydroisomerization are based upon aluminum phosphates, such as SAPO-11,SAPO-31, and SAPO-41. SM-3 is an example of a shape selectiveintermediate pore size SAPO, which has a crystalline structure fallingwithin that of the SAPO-11 molecular sieves. The preparation of SM-3 andits unique characteristics are described in U.S. Pat. Nos. 4,943,424 and5,158,665. Other shape selective intermediate pore size molecular sievesused for hydroisomerization are zeolites, such as ZSM-22, ZSM-23,ZSM-35, ZSM-48, ZSM-57, SSZ-32, offretite, and ferrierite.

A useful intermediate pore size molecular sieve is characterized byselected crystallographic free diameters of the channels, selectedcrystallite size (corresponding to selected channel length), andselected acidity. Desirable crystallographic free diameters of thechannels of the molecular sieves are in the range of from about 3.9 toabout 7.1 Å, having a maximum crystallographic free diameter of not morethan 7.1 and a minimum crystallographic free diameter of not less than3.9 Å. Optionally, the maximum crystallographic free diameter is notmore than 7.1 and the minimum crystallographic free diameter is not lessthan 4.0 Å. In some embodiments the maximum crystallographic freediameter is not more than 6.5 and the minimum crystallographic freediameter is not less than 4.0 Å. The crystallographic free diameters ofthe channels of molecular sieves are published in the “Atlas of ZeoliteFramework Types”, Fifth Revised Edition, 2001, by Ch. Baerlocher, W. M.Meier, and D. H. Olson, Elsevier, pp 10-15, which is incorporated hereinby reference.

An intermediate pore size molecular sieve which is useful in the presentinvention is described, for example, in U.S. Pat. Nos. 5,135,638 and5,282,958, the contents of which are hereby incorporated by reference intheir entirety. In U.S. Pat. No. 5,282,958, such an intermediate poresize molecular sieve has a crystallite size of no more than about 0.5microns and pores with a minimum diameter of at least about 4.8 Å andwith a maximum diameter of about 7.1 Å. The catalyst has sufficientacidity so that 0.5 grams thereof when positioned in a tube reactorconverts at least 50% of hexadecane at 370° C., a pressure of 1200 psig,a hydrogen flow of 160 mL/min, and a feed rate of 1 ml/hr. The catalystalso exhibits isomerization selectivity of 40 percent or greater(isomerization selectivity is determined as follows: 100×(weight %branched C₁₆ in product)/(weight % branched C₁₆ in product+weight % C¹³⁻in product) when used under conditions leading to 96% conversion ofnormal hexadecane (n-C₁₆) to other species.

If the crystallographic free diameters of the channels of a molecularsieve are unknown, the effective pore size of the molecular sieve can bemeasured using standard adsorption techniques and hydrocarbonaceouscompounds of known minimum kinetic diameters. See Breck, ZeoliteMolecular Sieves, 1974 (especially Chapter 8); Anderson et al. J.Catalysis 58, 114 (1979); and U.S. Pat. No. 4,440,871, the pertinentportions of which are incorporated herein by reference. In performingadsorption measurements to determine pore size, standard techniques areused. It is convenient to consider a particular molecule as excluded ifdoes not reach at least 95% of its equilibrium adsorption value on themolecular sieve in less than about 10 minutes (p/p_(o)=0.5 at 25° C.).Intermediate pore size molecular sieves will typically admit moleculeshaving kinetic diameters of 5.3 to 6.5 Å with little hindrance.

Hydroisomerization catalysts useful in the present invention comprise acatalytically active hydrogenation metal. The presence of acatalytically active hydrogenation metal leads to product improvement,especially Viscosity Index and stability. Typical catalytically activehydrogenation metals include chromium, molybdenum, nickel, vanadium,cobalt, tungsten, zinc, platinum, and palladium. If platinum and/orpalladium is used, the total amount of active hydrogenation metal istypically in the range of 0.1 to 5 weight percent of the total catalyst,usually from 0.1 to 2 weight percent, and not to exceed 10 weightpercent.

The refractory oxide support may be selected from those oxide supports,which are conventionally used for catalysts, including silica, alumina,silica-alumina, magnesia, titania and combinations thereof.

The conditions for hydroisomerization will depend on the properties offeed used, the catalyst used, whether or not the catalyst is sulfided,the desired yield, and the desired properties of the lubricant base oil.Conditions under which the hydroisomerization process of the currentinvention may be carried out include temperatures from about 260° C. toabout 413° C., optionally about 316° C. to about 399° C., or about 316°C. to about 371° C.; and pressures from about 15 to 3000 psig,optionally 100 to 2500 psig. The hydroisomerization pressures in thiscontext refer to the hydrogen partial pressure within thehydroisomerization reactor, although the hydrogen partial pressure issubstantially the same (or nearly the same) as the total pressure. Theliquid hourly space velocity during contacting is generally from about0.1 to 20 hr⁻¹, for example, from about 0.1 to about 5 hr⁻¹. Thehydrogen to hydrocarbon ratio falls within a range from about 1.0 toabout 50 moles H₂ per mole hydrocarbon, for example, from about 10 toabout 20 moles H₂ per mole hydrocarbon. Suitable conditions forperforming hydroisomerization are described in U.S. Pat. Nos. 5,282,958and 5,135,638, the contents of which are incorporated by reference intheir entirety.

Hydrogen is present in the reaction zone during the hydroisomerizationprocess, typically in a hydrogen to feed ratio from about 89 literH₂/liter feed to about 5343 liter H₂/liter feed, optionally from about178 liter H₂/liter feed to about 1781 liter H₂/liter feed. Hydrogen maybe separated from the product and recycled to the reaction zone.

Hydrotreating

The waxy feed to the hydroisomerization process may be hydrotreatedprior to hydroisomerization. Hydrotreating refers to a catalyticprocess, usually carried out in the presence of free hydrogen, in whichthe primary purpose is the removal of various metal contaminants, suchas arsenic, aluminum, and cobalt; heteroatoms, such as sulfur andnitrogen; oxygenates; or aromatics from the feed stock. Generally, inhydrotreating operations cracking of the hydrocarbon molecules, i.e.,breaking the larger hydrocarbon molecules into smaller hydrocarbonmolecules, is minimized, and the unsaturated hydrocarbons are eitherfully or partially hydrogenated.

Catalysts used in carrying out hydrotreating operations are well knownin the art. See, for example, U.S. Pat. Nos. 4,347,121 and 4,810,357,the contents of which are hereby incorporated by reference in theirentirety, for general descriptions of hydrotreating, hydrocracking, andof typical catalysts used in each of the processes. Suitable catalystsinclude noble metals from Group VIIIA (according to the 1975 rules ofthe International Union of Pure and Applied Chemistry), such as platinumor palladium on an alumina or siliceous matrix, and Group VIII and GroupVIB, such as nickel-molybdenum or nickel-tin on an alumina or siliceousmatrix. U.S. Pat. No. 3,852,207 describes a suitable noble metalcatalyst and mild conditions. Other suitable catalysts are described,for example, in U.S. Pat. Nos. 4,157,294 and 3,904,513. The non-noblehydrogenation metals, such as nickel-molybdenum, are usually present inthe final catalyst composition as oxides, but are usually employed intheir reduced or sulfided forms when such sulfide compounds are readilyformed from the particular metal involved. Some non-noble metal catalystcompositions contain in excess of about 5 weight percent, optionallyabout 5 to about 40 weight percent molybdenum and/or tungsten, and atleast about 0.5, and generally about 1 to about 15 weight percent ofnickel and/or cobalt determined as the corresponding oxides. Catalystscontaining noble metals, such as platinum, contain in excess of 0.01percent metal, for example, between 0.1 and 1.0 percent metal.Combinations of noble metals may also be used, such as mixtures ofplatinum and palladium.

Typical hydrotreating conditions vary over a wide range. In general, theoverall liquid hourly space velocity (LHSV) is about 0.25 to 2.0,optionally about 0.5 to 1.5. The hydrogen partial pressure is greaterthan 200 psia, often ranging from about 500 psia to about 2000 psia.Hydrogen recirculation rates are typically greater than about 9 literH₂/liter feed, for example, between about 178 liter H₂/liter feed toabout 891 liter H₂/liter feed. Temperatures in the reactor will rangefrom about 149° C. to about 399° C., for example, ranging from about230° C. to about 385° C.

Hydrofinishing

Hydrofinishing is a hydrotreating process that may be used as a stepfollowing hydroisomerization to provide the lubricant base oils used inthe ATFs of the present invention. Hydrofinishing is intended to improveoxidation stability, UV stability, and appearance of the lubricant baseoils by removing traces of aromatics, olefins, color bodies, andsolvents. As used in this disclosure, the term UV stability refers tothe stability of the lubricant base oil or the ATFs when exposed to UVlight and oxygen. Instability is indicated when a visible precipitateforms, usually seen as floc or cloudiness, or a darker color developsupon exposure to ultraviolet light and air. A general description ofhydrofinishing may be found in U.S. Pat. Nos. 3,852,207 and 4,673,487.

The lubricant base oils used in the ATFs of the present invention may behydrofinished to improve product quality and stability. Duringhydrofinishing, overall LHSV is about 0.25 to 2.0 hr⁻¹, optionally about0.5 to 1.0 hr⁻¹. The hydrogen partial pressure is greater than 200 psia,for example, ranging from about 500 psia to about 2000 psia. Hydrogenrecirculation rates are typically greater than about 9 liter H₂/literfeed, for example, between about 178 liter H₂/liter feed and about 891liter H₂/liter feed. Temperatures range from about 149° C. to about 399°C., for example, ranging from 230° C. to 316° C.

Suitable hydrofinishing catalysts include noble metals from Group VIIIA(according to the 1975 rules of the International Union of Pure andApplied Chemistry), such as platinum or palladium on an alumina orsiliceous matrix, and unsulfided Group VIIIA and Group VIB, such asnickel-molybdenum or nickel-tin on an alumina or siliceous matrix. U.S.Pat. No. 3,852,207 describes a suitable noble metal catalyst and mildconditions. Other suitable catalysts are described, for example, in U.S.Pat. Nos. 4,157,294 and 3,904,513. The non-noble metal (such asnickel-molybdenum and/or tungsten, and at least about 0.5, and generallyabout 1 to about 15 weight percent of nickel and/or cobalt determined asthe corresponding oxides. The noble metal (such as platinum) catalystcontains in excess of 0.01 percent metal, for example, between 0.1 and1.0 percent metal. Combinations of noble metals may also be used, suchas mixtures of platinum and palladium. Clay treating to removeimpurities is an alternative final process step to provide the lubricantbase oils used in the ATFs of the present invention.

Solvent Dewaxing

The process to make the lubricant base oils used in the ATFs of thepresent invention may also include a solvent dewaxing step following thehydroisomerization process. Solvent dewaxing optionally may be used toremove small amounts of remaining waxy molecules from the lubricant baseoil after hydroisomerization. Solvent dewaxing is done by dissolving thelubricant base oil in a solvent, such as methyl ethyl ketone, methyliso-butyl ketone, or toluene, or precipitating the wax molecules asdiscussed in Chemical Technology of Petroleum, 3rd Edition, WilliamGruse and Donald Stevens, McGraw-Hill Book Company, Inc., New York,1960, pages 566 to 570. Solvent dewaxing is also described in U.S. Pat.Nos. 4,477,333, 3,773,650 and 3,775,288.

Additive Package

The formulated ATF will typically include an additive package, which isa combination of several additives to provide an ATF with desirableproperties. Such additives typically include viscosity index improvers,fluidity modifiers, pour point depressants foam inhibitors, dispersants,detergents, antiwear agents, oxidation inhibitors, corrosion inhibitors,detergents, and friction modifiers. Often there is more than onerepresentative of each class present, so the total number of additivecomponents used to make an ATF is usually in the 10 to 20 range. Suchadditives are described in “Handbook of Lubrication and Technology”Volume 1, edited by George E. Totten, CRC Press, Boca Raton, Fla., 2006.The formulated ATF may comprise greater than 1 wt % of the additivepackage. In other embodiments, the formulated ATF may comprise greaterthan 5 wt % of the additive package and in further embodiments greaterthan 10 wt % of the additive package. As defined herein, the additivepackage does not include any Viscosity Index improver.

ATF Formulation

The ATF of the present invention may comprise less than 1.0 wt %Viscosity Index improver, optionally less than 0.5 wt % Viscosity Indeximprover, and in certain embodiments no Viscosity Index improver. TheATF of the present invention has a kinematic viscosity at −7° C. of lessthan 300 mm²/s, optionally less than 250 mm²/s, and in certainembodiments less than 200 mm²/s, and in other embodiments less than 150mm²/s. The ATF of the present invention has a kinematic viscosity at100° C. between 5.0 and 7.0 mm²/s, optionally between 5.0 and 6.0 mm²/s.The ATF of the present invention has a high VI, often greater than 150,and in certain embodiments greater than 200. The ATF of the presentinvention has a low Brookfield viscosity. Typically it has a Brookfieldviscosity at −40° C. of less than 10,000, for example, less than 6,000mPas. The ATF of the present invention optionally comprises less than0.5 wt % pour point depressant.

Generally VI improvers are oil soluble organic polymers, typicallyolefin homo- or co-polymers or derivatives thereof, of number averagemolecular weight of about 15000 to 1 million atomic mass units (amu). VIimprovers are generally added to lubricating oils at concentrations fromabout 0.1 to 10 wt %. They function by thickening the lubricating oil towhich they are added more at high temperatures than low, thus keepingthe viscosity change of the lubricant with temperature more constantthan would otherwise be the case. The change in viscosity withtemperature is commonly represented by the viscosity index (VI), withthe viscosity of oils with large VI (e.g. 140) changing less withtemperature than the viscosity of oils with low VI (e.g. 80).

Major classes of VI improvers include: polymers and copolymers ofmethacrylate and acrylate esters; ethylene-propylene copolymers;styrene-diene copolymers; and polyisobutylene, VI improvers are oftenhydrogenated to remove residual olefin. VI improver derivatives includedispersant VI improver, which contain polar functionalities such asgrafted succinimide groups.

Pour point depressants are often needed for oils that have a tendency toform wax crystals at low temperature. Pour point depressants are highmolecular weight polymers that tend to prevent the growth andaggregation of wax crystals. Examples of pour point depressants arealkylated wax naphthalenes, styrene ester polymers, ethylene vinylacetate copolymers, polyfumarates, and polyalkylmethacrylates.

The ATFs of the present invention exhibit improved fuel economy due tothe high Viscosity Index of the lubricant base oils used in the ATFs.The high Viscosity Index of the lubricant base oils used in the ATFsprovides an ATF of the present invention that avoids having too low aviscosity at higher operating temperatures and too high a viscosity atlower operating temperatures. Since the ATFs of the present invention donot exhibit too high viscosity at lower operating temperatures, the ATFsof the present invention have improved fuel economy.

EXAMPLES

The invention will be further explained by the following illustrativeexamples that are intended to be non-limiting.

Oils A-D of Table 1 comprised Group III lubricant base oils and variousVI improvers.

TABLE 1 Reference Oil A Oil B Oil C Oil D Kinematic viscosity @ 100° C.,mm²/s 7.47 7.48 5.54 7.67 5.26 Kinematic viscosity @ 40° C., mm²/s 34.036.9 24.9 34.1 19.6 Kinematic viscosity @ −7° C., mm²/s 312 400 239 296129 Brookfield viscosity @ −40° C., mPa-s 18400 16800 5580 7430 2520Viscosity Index 196 176 171 206 225 Ravenfield viscosity @ 150° C., mPas2.02 2.60 2.02 2.15 1.55 Cold Cranking Simulator @ −25° C., mPas 13651773 <1300 <1300 <1300 Viscosity after shearing (KRL 20 hrs) KinematicViscosity @ 100° C., mm²/s 4.7 6.6 5.14 5.13 3.6 Change −37% −7% −33%−12% −32% Vehicle Fuel Economy @ −7° C., % 0.00, +0.1, −0.4 −1.7, −1.2+0.5 +0.2 +2.3

The fuel economy test was a variation on the standard European fueleconomy test, with the principle difference being that the test chamberwas held at −7° C. (the temperature at which emission tests are run ongasoline-powered vehicles) rather than the standard +20° C.

The test was a “rolling road” test, using a complete car, in this case aBMW 525d, in a chassis dynamometer, and relates to the cold-start andwarm-up phase of the European driving cycle.

Previous experience indicated that “cold starts” are a very importantcontributor to fuel economy and that discrimination between oils wasmore likely to be seen by running at this temperature (the observedcorrelation between measured fuel economy and oil viscosity at −7° C.seems to confirm the validity of this assumption). The fuel economyvalues are a composite of the results from the City and Extra-Urbandriving cycles (the other two cycles of the standard test, steady-statedriving at 90 and 120 km/hour, were not run). The fuel economy results(given in percentage versus reference) were correlated with kinematicviscosity at −7° C. to give the following relationship:

F.E.=0.0134*KV+3.9501.

Three different lubricant base oils were prepared from a hydrotreatedFischer-Tropsch wax by hydroisomerization dewaxing the Fischer-Tropschwax over a Pt/SAPO-11 catalyst, hydrofinishing, and vacuum distillingthe product into three different grades. The Fischer-Tropsch wax wascomposed of several different hydrotreated Fischer-Tropsch waxes, allmade using a Co-based Fischer-Tropsch catalyst, and all of which had <10ppm Sulfur, <10 ppm Nitrogen, <0.50 wt % Oxygen, >85 wt % N-Paraffins(by gas chromatography), and according to ASTM D6352 T₁₀ Boiling RangeDistribution of about 288° C. to about 371° C., T₉₀ Boiling RangeDistribution of about 538° C. to about 582° C., and T₉₀-T₁₀ BoilingRange Distribution of >154° C. The different lubricant base oils wereused to formulate Oils 1-2 in Table 2.

TABLE 2 Oil 1 Oil 2 Oil 3 Oil 4 Oil 5 Oil 6 GTL Lubricant Base Oil(s)84.7% 84.7% — — — — Group III Lubricant Base Oil(s) — — 84.7% 84.7%84.7% — Poly Alpha Olefin(s) (PAO) — — — — — 84.7% Additive Package  15%   15%   15%   15%   15%   15% Pour Point Depressant  0.3%  0.3% 0.3%  0.3%  0.3%  0.3% Kinematic viscosity @ 100° C., mm²/s 5.31 5.325.38 5.50 5.39 5.33 Kinematic viscosity @ 40° C., mm²/s 23.5 24.4 26.227.7 26.8 26 Kinematic viscosity @ −7° C., mm²/s 220 248 302 343 324 301Brookfield viscosity @ −40° C., mPas 5740 5200 8400 12800 12800 5580Viscosity Index 170 160 146 140 141 145 Expected fuel economy versusreference, % +1.0 +0.6 −0.1 −0.6 −0.4 −0.1

Oils 1-6 comprised the same Additive Package and Pour Point Depressant,no VI improver, and were formulated to a target kinematic viscosity at100° C. of 5.4 mm²/s. For oils with the same kinematic viscosity at 100°C., an oil with a higher VI will have a lower viscosity at temperaturesbelow 100° C. The GTL lubricant base oil of Oil 1 had a kinematicviscosity at 100° C. of 4.039 mm²/s, and a VI of 150. Oil 2 comprised amixture of two GTL lubricant base oils, 60% of one which had a kinematicviscosity at 100° C. of 3.081 mm²/s and a VI of 124, and 24.7% of onewhich had a kinematic viscosity at 100° C. of 7.969 mm²/s and a VI of162.

The kinematic viscosities at −7° C. of Oil 1 (220 mm²/s) and Oil 2 (248mm²/s) are remarkably low, and notably lower than for an equivalentformulation using Group III lubricant base oils (Oil 3=302 mm²/s; Oil4=343 mm²/s; and Oil 5=324 mm²/s) or Poly Alpha Olefins (PAO) (Oil 6=301mm²/s). The kinematic viscosity at −7° C. is a significant contributorto fuel economy.

The expected fuel economy was calculated using the above relationship:

F.E.=0.0134*KV+3.9501.

While the present invention has been described with reference tospecific embodiments, this application is intended to cover thosevarious changes and substitutions that may be made by those of ordinaryskill in the art without departing from the spirit and scope of theappended claims.

1. An automatic transmission fluid comprising: a. a lubricant base oilhaving a Viscosity Index greater than a Viscosity Index Factor ascalculated by the following equation:Viscosity Index Factor=28×ln(Kinematic Viscosity at 100° C.)+90; b. anautomatic transmission fluid additive package; and c. less than 1.0 wt %Viscosity Index improver; wherein the automatic transmission fluid has akinematic viscosity at −7° C. of less than 300 mm²/s, and a kinematicviscosity at 100° C. between 5.0 and 6.0 mm²/s.
 2. The automatictransmission fluid of claim 1, comprising greater than 5 wt % automatictransmission fluid additive package.
 3. The automatic transmission fluidof claim 1, wherein the kinematic viscosity at −7° C. is less than 250mm²/s.
 4. The automatic transmission fluid of claim 1, wherein thekinematic viscosity at −7° C. is less than 200 mm²/s.
 5. The automatictransmission fluid of claim 1, wherein the kinematic viscosity at −7° C.is less than 150 mm²/s.
 6. The automatic transmission fluid of claim 1,wherein the automatic transmission fluid has a Viscosity Index ofgreater than
 150. 7. The automatic transmission fluid of claim 1,wherein the automatic transmission fluid has a Viscosity Index ofgreater than
 200. 8. The automatic transmission fluid of claim 1,wherein the automatic transmission fluid has a Brookfield viscosity at−40° C. of less than 10,000 mPas.
 9. The automatic transmission fluid ofclaim 1, wherein the automatic transmission fluid has a Brookfieldviscosity at −40° C. of less than 6,000 mPas.
 10. The automatictransmission fluid of claim 1, wherein the lubricant base oil is derivedfrom a waxy feed.
 11. The automatic transmission fluid of claim 1,wherein the lubricant base oil is Fischer-Tropsch derived.
 12. Theautomatic transmission fluid of claim 1, comprising less than 0.5 wt %Viscosity Index improver.
 13. The automatic transmission fluid of claim1, comprising approximately 0 wt % Viscosity Index improver.
 14. Theautomatic transmission fluid of claim 1, further comprising less than0.5 wt % pour point depressant.
 15. The automatic transmission fluid ofclaim 1, wherein the lubricant base oil has a Viscosity Index greaterthan the Viscosity Index Factor plus
 5. 16. The automatic transmissionfluid of claim 1, wherein the lubricant base oil has a Viscosity Indexgreater than the Viscosity Index Factor plus
 15. 17. An automatictransmission fluid comprising: a lubricant base oil having a ViscosityIndex greater than a Viscosity Index Factor plus 15, wherein theViscosity Index Factor is calculated by the following equation:Viscosity Index Factor=28×ln(Kinematic Viscosity at 100° C.)+90; andwherein the automatic transmission fluid has a kinematic viscosity at−7° C. of less than 300 mm²/s and a kinematic viscosity at 100° C.between 5.0 and 7.0 mm²/s.
 18. The automatic transmission fluid of claim17, wherein the lubricant base oil is derived from a waxy feed;
 19. Theautomatic transmission fluid of claim 17, wherein the kinematicviscosity at −7° C. is less than 250 mm²/s.
 20. A process for producingan automatic transmission fluid comprising: a. providing a lubricantbase oil having a Viscosity Index greater than a Viscosity Index Factoras calculated by the following equation:Viscosity Index Factor=28×ln(Kinematic Viscosity at 100° C.)+90; b.blending the lubricant base oil fraction with an automatic transmissionfluid additive package; and c. isolating an automatic transmission fluidcomprising less than 1.0 wt % Viscosity Index improver, wherein theautomatic transmission fluid has a kinematic viscosity at −7° C. of lessthan 300 mm²/s, and a kinematic viscosity at 100° C. between 5.0 and 7.0mm²/s.
 21. A process for producing an automatic transmission fluidcomprising: a. performing a Fischer-Tropsch synthesis to provide aproduct stream; b. isolating from the product stream a waxy feed; c.hydroisomerizing the waxy feed using a shape selective intermediate poresize molecular sieve comprising a noble metal hydrogenation componentunder conditions of about 316° C. to about 399° C.; d. isolating anisomerized oil; e. hydrofinishing the isomerized oil to provide aFischer-Tropsch derived lubricant base oil having a Viscosity Indexgreater than a Viscosity Index Factor as calculated by the followingequation:Viscosity Index Factor=28×ln(Kinematic Viscosity at 100° C.)+90; f.blending the Fischer-Tropsch derived lubricant base oil with anautomatic transmission fluid additive package; and g. isolating anautomatic transmission fluid comprising less than 1.0 wt % ViscosityIndex improver, wherein the automatic transmission fluid has a kinematicviscosity at −7° C. of less than 300 mm²/s, and a kinematic viscosity at100° C. between 5.0 and 7.0 mm²/s.
 22. A process for producing anautomatic transmission fluid comprising: a. performing a Fischer-Tropschsynthesis to provide a product stream; b. isolating from the productstream a waxy feed; c. hydroisomerizing the waxy feed using a shapeselective intermediate pore size molecular sieve comprising a noblemetal hydrogenation component under conditions of about 316° C. to about399° C., wherein the intermediate pore size molecular sieve is selectedfrom the group consisting of SAPO-11, SAPO-31, SAPO-41, SM-3, ZSM-22,ZSM-23, ZSM-35, ZSM-48, ZSM-57, SSZ-32, offretite, ferrierite, andcombinations thereof and the noble metal hydrogenation component isselected from the group consisting of platinum, palladium, andcombinations thereof; d. isolating an isomerized oil; e. vacuumdistilling the isomerized oil to provide a lubricant base oil; f.hydrofinishing the lubricant base oil to provide a Fischer-Tropschderived lubricant base oil having a Viscosity Index greater than aViscosity Index Factor as calculated by the following equation:Viscosity Index Factor=28×ln(Kinematic Viscosity at 100° C.)+90; g.blending the Fischer-Tropsch derived lubricant base oil with anautomatic transmission fluid additive package; and h. isolating anautomatic transmission fluid comprising less than 1.0 wt % ViscosityIndex improver, wherein the automatic transmission fluid has a kinematicviscosity at −7° C. of less than 300 mm²/s, and a kinematic viscosity at100° C. between 5.0 and 7.0 mm²/s.